A solid electrolytic capacitor in which an equivalent series resistance (hereinafter referred to as an ESR) value is low in a high frequency region has conventionally been known. An example of such a conventional solid electrolytic capacitor is disclosed in Japanese published unexamined application No. 2001-217159.
FIG. 2 is a cross-sectional view for illustrating the structure of a conventional solid electrolytic capacitor. The structure of the conventional solid electrolytic capacitor will herein after be described in reference to FIG. 2.
As shown in FIG. 2, in the conventional solid electrolytic capacitor, a virtually plate-like anode 101 comprised of a tantalum porous sintered body that is fabricated by sintering tantalum powder with an average grain size of approximately 2 μm, in vacuum, is formed on an anode lead 101a comprised of tantalum so as to cover a portion of the anode lead 101a. 
A dielectric layer 102 comprised of tantalum oxide is formed on the anode 101 so as to cover an area surrounding the anode 101. Also, an electrolyte layer 103 comprised of polypyrrole is formed on the dielectric layer 102 so as to cover an area surrounding the dielectric layer 102.
An intermediate layer 104 containing a mixture of polypyrrole and carbon particles is formed on the electrolyte layer 103 so as to virtually uniformly cover an area surrounding the electrolyte layer 103.
A cathode 105 is formed on the intermediate layer 104 so as to cover an area surrounding the intermediate layer 104. The cathode 105 is comprised of a first electrically conductive layer 105a consisting mainly of graphite particles, which is formed so as to cover the area surrounding the intermediate layer 104; and a second electrically conductive layer 105b consisting mainly of silver particles, which is formed so as to cover an area surrounding the first electrically conductive layer 105a. 
The top surface of an area surrounding the cathode 105 is formed with an electrically conductive adhesive layer 106, through which the cathode 105 and a cathode terminal 107 are interconnected. Also, an anode terminal 108 is welded onto the anode lead 101a exposed from the anode 101. A mold-packaging resin 109 is formed around the second electrically conductive layer 105b, the cathode terminal 107 and an anode terminal 108 such that respective edges of the cathode and anode terminals 107 and 108 can be located outside. The conventional solid electrolytic capacitor is thus configured.
As described above, in the conventional solid electrolytic capacitor, the intermediate layer 104 containing the mixture of polypyrrole and carbon particles, which comprise the electrolyte layer 103 and the cathode 105 respectively, is formed between the electrolyte layer 103 and the cathode 105.